import java.util.Stack;

class MyQueue {
    public Stack<Integer> s1;
    public Stack<Integer> s2;

    public MyQueue() {
    s1=new Stack<>();
    s2=new Stack<>();
    }
    
    public void push(int x) {
        s1.push(x);
    }
    
    public int pop() {
        if(empty()){
            return -1;
        }
        if(s2.isEmpty()){
            while(!s1.empty()){
                int x= s1.pop();
                s2.push(x);
            }
        }
        return s2.pop();


    }
    
    public int peek() {
        if(empty()){
            return -1;
        }
        if(s2.isEmpty()){
            while(!s1.empty()){
                int x= s1.pop();
                s2.push(x);
            }
        }
        return s2.peek();
    }
    
    public boolean empty() {
    return s1.isEmpty()&&s2.isEmpty();
    }
}

/**
 * Your MyQueue object will be instantiated and called as such:
 * MyQueue obj = new MyQueue();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.peek();
 * boolean param_4 = obj.empty();
 */